Bottom line is that I think the implication here is that your phone key can unlock the wrong car. Safe to say that didn't happen. If someone forgets and leaves their phone in their car and has not set up PIN to drive, anyone can get in and drive off. Doesn't mean people are walking around able to unlock the wrong car.
Even with the phone-left-in-car scenario, a lot has to align for you to not notice it isn't your Tesla. You have to be roughly the same height as the real owner, listen to the same music station (or no music), have the mirrors and steering wheel adjusted the same way, screen layout and options the same, etc.
Mike